ROLLING AND ROLLER-DRAWING OF POLY(ETHER ETHER KETONE) SHEETS

Crystalline and amorphous sheets of poly(ether ether ketone) (PEEK) were stretched using rolling and roller-drawing techniques. The mechanical properties and the molecular orientation in the stretched sheets were studied by tensile tests, wide angle X-ray diffraction (WAXD), and birefringence. In the case of crystalline PEEK sheets, the Young's modulus and the tensile strength increase with increasing draw ratio; the Young's modulus reaches 9.9 GPa at the highest draw ratio. The crystal c-axis and amorphous molecular chains orient in the draw direction, and the (100) plane is aligned in the sheet plane of the rolled and roller-drawn sheets. In the roller-drawing experiments of amorphous PEEK sheets, the draw ratio is confined to a range of 2.8 approximately 3.1 and is not sensitive to processing conditions. Stress-induced crystallization takes place in the roller-drawing process of amorphous PEEK sheets. The degree of crystallinity and birefringence increase with increasing draw velocity.